Number of subsets of {1..n} containing n whose product is divisible by their sum.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =1a(5) =5a(6) =9a(7) =15a(8) =30a(9) =65a(10) =138a(11) =274a(12) =563a(13) =1149a(14) =2441a(15) =5110a(16) =9090a(17) =19645a(18) =37524a(19) =79178a(20) =156697a(21) =324182a(22) =663749a(23) =1353984a(24) =2529510a(25) =5088926a(26) =10686159a(27) =19987129a(28) =40800192a(29) =85303150